Accretion definition, an increase by natural growth or by gradual external addition; growth in size or extent. See more.
Alveoli are tiny sacs within our lungs that allow oxygen and carbon dioxide to move between the lungs and bloodstream. Learn more about how they function and quiz your knowledge at the end.
The basic function of alveoli is exchange of gases. Its structure is the site where the gaseous exchange during respiration takes place. These structures are surrounded by capillaries carrying blood. The exchange of carbon dioxide in the blood from these capillaries occurs through the walls of alveolus.